U.S. Pat. Nos. 4,638,672, 4,812,049, 5,363,699 and 5,814,738 disclose fluid flow meters and fluid dispersing and mixing devices which are characterized by a unique static fluid flow displacement member which is mounted symmetrically within a conduit and which is effective to linearize fluid flow through the conduit within a region defined between the displacement member and the interior surface of the conduit and to flatten the velocity profile of fluid flow in the conduit both upstream and downstream from the displacement member. The apparatus ensures reliable measurement of fluid flow conditions within the conduit and also provides for homogeneous blending and dispersing of diverse fluids and/or fluids containing particulate matter.
The unique fluid flow meters and mixers are made and sold under the registered trademark “V-CONE” by McCrometer, Inc. of Hemet, Calif., which is the owner of the above patents and the assignee of the present invention.
The fluid flow displacement member in the V-CONE devices is comprised of two frustums, usually conical, joined at their larger ends and mounted coaxially in an individualized section of conduit. The frustums are mounted substantially normal to the axis of the section and the direction of fluid flow and with their peripheries spaced symmetrically inward from the interior surface of the conduit section. Depending upon the dimensions of the displacement member relative to the internal diameter of the conduit, the displacement member is effective to linearize fluid flow over a range of flow rates through the section.
In some embodiments, the displacement member is made by joining two frustums together at their larger ends, usually by welding. The frustum facing in the upstream direction is customarily joined, e.g., by welding, at its upstream and smaller end to a pipe or tube which extends through the displacement member to its downstream face and through which a pressure reading is taken or through which a secondary fluid is introduced for mixing with a primary fluid flowing through the conduit. The pipe or tube is bent outwardly and extends through the wall of the conduit section upstream from the displacement member. The pipe or tube is joined, e.g., welded, to the wall of the conduit section and conveniently serves as the means for mounting the displacement member coaxially within the section.
In the embodiments above described, a separate flowmeter and its associated flow sensing devices are required for each of the various sizes of flowmeters needed for linearlizing and measuring fluid flows over respective ranges of flow rates.
U.S. Pat. No. 5,814,738 discloses an embodiment of the V-CONE device wherein the fluid flow displacement member is removeably and replaceably mounted in the downstream end of the conduit section so that a given displacement member can be removed and replaced by one or more different displacement members in order to accommodate different fluids and different ranges of fluid flow through the conduit section. In this way, a single section of conduit, i.e., a single meter body, can be used with a variety of displacement members to accommodate various liquids and gases and a broad range of flows through the meter body.
The latter embodiment of the device also provides flow measurement taps through the wall of the conduit section or meter body so that no measurement taps or other holes or passages are required in the displacement member. However, it has since been discovered that for some fluids, especially high velocity gases, measurement of the pressure at the downstream side of the displacement member by a tap in the conduit wall is not as accurate as the downstream measurements obtained with the earlier embodiments of the V-CONE device.